A virtual machine (VM) is a software implementation of a computing environment that can execute its own operating systems and programs as if it were a physical computer. Virtual machines are created within a virtualization layer that can be used to create many individual virtual machine environments. While virtual machines can share the physical resources of a single computer, they can remain completely isolated from each other as if they were separate physical machines. Consequently, if, for example, a virtual machine in a physical server crashes or is compromised, the other virtual machines on that physical server remain available. Isolation is one reason why the availability and security of applications running in a virtual environment can be superior to applications running in a traditional, non-virtualized system.